In IC manufacturing methods, the wafer is treated with plasma by a plasma processing device (hereafter called MMT apparatus) utilizing a modified magnetron type plasma source that generates a high-density plasma by means of an electrical field and a magnetic field.
The MMT apparatus includes a processing chamber, a susceptor, a cylindrical electrode, a cylindrical magnet, a shower head, and an exhaust vent. To perform plasma processing, a wafer serving as the substrate to be processed is mounted on the susceptor in the processing chamber maintained in an air-tight state. Reactive gas is supplied into the processing chamber via a shower plate and the processing chamber is maintained at a specified pressure. An electrical field and a magnetic field are formed by supplying high-frequency electrical power to the cylindrical electrode to induce magnetron discharge. At this time, electrons discharged from the cylindrical electrode rotate in a continual cycloid movement while drifting, the ionization rate is boosted due to a longer electron life and high-density plasma is generated. The MMT apparatus in this way, excites and breaks down reactive gas for plasma processing including oxidizing, nitriding, diffusing, film-forming, and etching of the wafer surface (for example in patent document 1).
In conventional MMT apparatuses, the susceptor is usually manufactured from aluminum nitride (AlN). Also in conventional MMT apparatuses, the susceptor sometimes contains a heater for heating the wafer, and a high-frequency electrode for applying a bias voltage. The high-frequency electrode incidentally is formed in a lattice shape (mesh shape) from material with a high melting point such as molybdenum (Mo).    Patent document 1: Japanese Patent Non-Examined Publication No. 2001-196354